Control method and mechanism for photographic printers



May 20, 1941. w. D. FOSTER ETAL 2,243,047

CONTROL METHOD AND MECHANISM FOR PHOTOGRAPHIC PRINTERS Filed Sept. 24, 1934 4 Sheets-Sheet 1 w UM D- ATTORNEY y 20, 1941. w. D. FOSTER EAL 2 243,041

CONTROL METHOD AND MECHANISM FOR PHOTOGRAPHIC PRINTERS Filed Sept. 24, 1934 4 Sheets-Sheet 2 5 (NW D- /55 IE. ATTORNEY y 1941- w. D. FOSTER ETAL 2,243,047

CONTROL METHOD AND MECHANISM FOR PHOTOGRAPHIC PRINTERS Filed Sept. 24, 1934 4 Sheets-Sheet 3 ATTORNEY y 1941- w. D. FCSSTER ETAL 2,243,047

CONTROL METHOD AND MECHANISM FOR PHOTOGRAPHIC PRINTERS Filed Sept. 24, 1934 4 Sheets-Sheet 4 ATTO RN EY Patented May 20, 1941 CONTROL METHOD AND MECHANISM FOR PHO'IDGRAPHI'C PRINTERS Warren Dnnham Foster, Bergen County, N. J., deceased, late oi. Pittsburgh, Pa., by Peoples- Pittshurgh Trust Company, executor, Pittsburgh, PL, assignments,

Washington Township,

and Earle L. Parmelee,

asaignors, by direct and mesne to Kinatome Patents Corporation,

Bidgewood, N. 1., a corporation of New York Application September 24, 1934, Serial No. 745,320

28 Claims.

This application is a continuation in part of our application Serial Number 706,437, filed J anuary 12, 1934, now Patent No. 2,213,212, which in turn is a division of our application Serial Number 105,159, filed April 28, 1926, which on January 16, 1934, matured as Patent Number 1,944,024. scribe and claim means operated by light passed through a film for controlling in a particular manner desired various operations of the film handling apparatus itself and operations of apparatus associated therewith. In our immediately parent application, we describe and claim apparatus in which the speed of operation of the film feeding mechanism is determined by such light-responsive signals as is also the amount of light which is effective upon the film. In the present application, we apply our invention specifically to a printing or reversing apparatus. A primary object, therefore, of the present invention is specifically to apply the subject matter generally set out in our parent applications to a particular type of film handling apparatus operated in particular ways.

In our parent applications, we control the apparatus by means of changes in the translucency of successive portions of the moving film. A light beam, modified by such successive portions, operates a control mechanism. In the present application, such'changes may be caused. also by signalling portions applied to the film or by the density of the film itself. An object of the present invention, therefore, is to improve upon the parent applications by using the density of the film itself, alternatively to signals which are applied to predetermined portions of the film, to

control the speed of operation of the film and the light effective thereupon.

As is well understood in the motion picture art, in producing a positive film from a negative film or in reversing a negative film into a positive film, it is necessary to modify the eflectiveness of the printing light in accordance with changes in the density of the successive portions of the negative so that the resulting positive will be of uniform density. In preferred forms of our present invention, we accomplish such modification by means controlled by the film itself. We may exercise this control in various ways, as preferably by introducing resistance into the circuit of the light source or alternatively by maintaining the light source constant and varying the effectiveness of the light imp l upon the film by changing the speed of movement of the film through the light beam, thereby varying In both of said applications we de-' the exposure. In order to avoid the difllculties attendant upon too great variations in speed, we may use such variations to determine the minor and delicate changes in intensity, and rely upon screens or other light retarding instrumentalities, automatically interposed in the light beam, to accomplish the major variations. Alternatively, we may accomplish such minor variations by changes in the resistance in circuit with the printing light while using screens for the major variations. By such methods, we are able "Go limit the use of resistance in the circuit of the light source to such small amounts as will cause no change in color values and hence in printing effectiveness and secure full. range of gradation of light values by such secondary means.

-An important object of our invention is the control of a printing operation by methods and/or means which do not depend upon any change in the beam of a printing light or in the source thereof, as by varying the speed at which a film is moved through a beam of light of unchanging intensity.

Among the further objects of our invention are the provision of improved means for:

l. Controlling the placing of resistance in cirsuit with the motor of a film handling apparatus and its removal therefrom;

2. Controlling the placing of resistance in cirsuit with the light source of a film handling apparatus and its removal therefrom;

3. Operating light modifying means;

4. Operating means for modifying light from a constant source;

5. Operating means for modifying a light source;

6. Controlling the speed of film movement by a brake, preferably fiuid operated, applied to the driving mechanism;

7. Controlling the speed of film movement by applying a braking force to the driving motor, preferably by the introduction of resistance into the field of a motor.

It also is to be noted that we supply means whereby the introduction of one light modifying or circuit changing means into effective relation with the film automatically removes from such effective relation whatever other light modifying or circuit changing means previously may have been in such relation.

"A further object of our invention is the provision ofmeans whereby fade in" and fade out may be automatically accomplished in a printing operation.

Another object of our invention is the reduccomplish the more-extreme changes in desired light intensity or light efiectiveness by one means and the finer changes by another. 4

We also provide method and/or means whereby the light changes in a printing operation may be in part automatic and in part under the control of an operator.

A most important object of our invention is to provide an automatic printing or reversal machine in which the film itselI controls the entire operation either through signals placed upon it or alternatively through the densityoi the negative itself in combination with means responsive to radiant energy.-

Throughout this specification we refer to photographic printing and to the reversal of a photographic negative into a pomtive. So far as our invention is concerned, the two operations may be considered as interchangeable. Our invention can be applied in some of its phases to either step printing or continuous printing.

It has been proposed to change the efiectiveness'oi a light beam impinging upon a film by means of the movement of a shutter or a diaphragm operated by mechanism which is actuated by a photo-electric cell or similar instrumentality. Such a construction necessitates the rapid movement 01' a relatively large mass of material for very short distances in order to give the fine gradations which are necessary in a printing operation. An important object 01' the present invention is to improve upon such mechanism either by eliminating screens or shutters entirely and depending upon resistance in circuit with the printing light source or with the motor or upon other means of changing motor speed, and alternatively upon such means to accomplish the finer gradations and the movement 01 screens or the like to and from predetermined positions to accomplish the major gradations. It will thus be readily understood that the finer changes which determine the efiectiveness of a printing operation are under the control, according to our invention, of very much more responsive and easily and accurately operated instrumentalities than those previously proposed.

Other objects, characteristics, and advantages will be apparent from the following portion of this specification, the attached drawings and the subjoined claims. For purposes of illustration only we are showing only certain preferred forms of our invention but it will be readily understood that we are in no way limiting ourselves to these particular exemplifications since changes may be made therein without departing from the spirit of our invention or the scope of our broader claims.

In the drawings:

Figure 1 is a diagrammatic view showing means for moving light retarding screens into and out of the beam or a printing light, certain parts being omitted for clarity;

Figure 2 is a view taken along the line 2-4 of Figure 1 looking in the direction of the arrows and shows mechanism for operating such screens;

Figure 3 is a partial front elevational view of a gate showing one form of window or aperture;

Figure 4 is a vertical sectional view on the line 4-4 of Figure 3;

Flgure 5 is a view similar to Figure 3 il1ustrat-' ing a modified form oi aperture;

Figure 6 is a detailed view on a large scale oi a portion or the film illustrating one manner in which any of the signals herein referred to maybe applied to a film in the space provided between the individual images or "frames," the controls being in the form of opaque portions;

Figure 'I is a view corresponding to Figure 6, but showing the control exercised by predetermined translucent portions placed in the space provided in a margin of a film;

Figure 8 is a view corresponding to Figure 7, but showing the control exercised by predetermined opaque portions placed in such margins;

Figure 9 is a sectional view corresponding to Figure .8; v

Figure 10 is a view corresponding to Figure 1, but showing the control of the effective printing light exercmed by the means of resistance placed in 1and removed from the circuit of the printing it t;

Figure 11 is a partial view corresponding to Figure 10, but showing the control exercised by means of changes in motor speed;

Figure 12 is a view corresponding to Figure 2, but showing the control exercised by means or resistance gradually added to and removed from the circuit of the motor;

Figure 13 shows our invention as applied to a manually operable device:

' Figure 14 is a fragmentary view corresponding to Figure 13, but showing an eye piece substituted iigr the photoelectric indicating device oi Figure Figure 15 is a detailed view showing shielding means for the light screens of Figure 1;

Figure 18 shows our invention as applied to a printer as distinct from an apparatus in which a film isreversed;

Figure 1-7 is a diagrammatic view showing our invention applied directly to resistance in circuit with the printing light source and controlled in accordance with the characteristics of the negative film Figure 18 corresponds to Figure 17, but shows the control exercised by means of resistance in the motor circuit;

Figure 19 corresponds to Figure 18, but shows the control exercised by a special braking winding applied to the motor.

Figure 20 corresponds to Figures 18 and 19, but

. shows the control applied by means of a fluid brake in the motion transmitting train 01' .the motor and feed sprocket;

Figure 21 is a diagrammatic view showing our invention as applied to the combination of means for changing the intensity of the printing light and the use of light retarding screens;

Figure 22 shows such screens in the form of filters or the type which change the density of the beam without afiecting the wave length;

Figure 23 shows a form alternative to that of Figure 22 in which modification oi the light is eflectuated by wire mesh screens;

Figure 24 is a diagrammatic view of our invention as of the form of Figure 19 as applied to a reversal process;

Figure 25 shows a fixed heat and light absorbing screen interposed between the printing light source and the film;

Figure 26 shows mechanism for operating light retarding screens, such as those shown in Figures 22 and 23, in the form of the invention shown in Figure 21.

and 8 of the drawings.

ber of positions upon the film, relatively difiercut one from the other, for the signals which are employed. The mounting of the mirrors is later described. Cooperating with the several mirrors l4, l and I8, and with additional mirrors if necessary, are signals placed upon any desired portion of the film as taught in our parent applica tion and for example as show'n in Figures 6, 7, Such signals and their operation may be as described in our parent applications. As shown in Figure 6, signalling portions indicated at I! and I3 may be placed between the frames or picture bearing portions of the film and cooperate with appropriately placed mirrors, to actuate photo-electric cells or other instrumentalities responsive to radiant energy. Similarly, as indicated in Figure '7, translucent signalling portions such as and 2! may be employed. Similarly as indicated in Figure 8, opaque signalling portions 22 and 23 may be placed upon the edge of the film and may co operate with appropriate mirrors or other refiecting means. Either or both edges of the film may be employed. When the signal itself is translucent, it is necessary to render the remainder of the edge opaque, as can very readily be done. A masque may be applied, and an opaque dye brushed on by hand, or the negative may be fed through a simple machine in which a brush applies the dye to the edge. This task needs be done but once to any one negative. The dye may be of such a character that later it may readily be removed by means which do not injure the film. One advantage of the use of translucent signals is that the remaining nonsignalling portion of the edge is rendered opaque thus blanking out various edge markings, such as the name of the maker of the film, which might otherwise interfere with a signalling operation.

In such cases as it is desired to make use of signals which cause each cell to emit a plurality of different responses, the width of the signalling portions may be varied.

A common practice in motion picture printing is to mutilate an edge of the film by forming notches which actuate members which control the mechanism which determines the intensity of the printing light. Alternatively metal contact clips may be added. Such indicia, as is readily apparent, weaken the film and often cause its breakage. Signals such as we employ do not have these disadvantages. Moreover, once a film is notched, according to the practice of one laboratory, it is not in proper condition for printing by another laboratory, and it is permanently impaired. Metal contact clips may be removed after use by one laboratory (but seldom are), but such removal often injures the negative. With signals of our type, not only is the negative entirely unimpaired, but the signals may be easily removed without the slightest injury to the film. Thus we have provided a method of automatic film printing which obviates one of the most common complaints of owners of nega tives.

Any desired type of photo-electric cell may be used, with signals of an opaque or translucent type as is appropriate to the particular cell.

Photolytic material may be employed, or a thermo-couple. For simplicity, in the subioined claims, we make use of the term "photo-electric cell, but it is to be understood thatwe employ this term generically as meaning any signalling device responsive to radiant energy, whether the particular response is to radiant energy in the form of visible light or invisible light or of heat, and whether that response takes the form of modifying an electric current already produced or of producing an electrical current.

It is of course understood that in the forms of our invention in which we make use of signals, the negative is timed before being printed. That is to say, the density of the negative is determined, and the appropriate signals, as described above or in our parent applications, to modify the printing light in accordance with such determination, are placed upon the film.

As a signalling impulse resulting from light passed through a signal as described above is reilected by the mirror H to a photo-electric cell 21, the electrical impulse so produced or modifled passes through a lead 23 and operates a magnet 23 which moves a switch member to such position that it closes a lead 3i and operates a solenoid 32 which rotates a screen 33 into light intercepting position against power of a spring 35. A slotted arm 36. cooperating with a pin 31, is eii'ective to move the standard 33 of the screen 33 to the right. as shown in Figure 2. As the screen 33 is moved almost completely to the right as shown in this figure. a cam formation III in the rim of the screen 33 engages with a detent ll mounted upon a shaft 2 and operated by a spring 43 which holds the screen 33 in light intercepting position against the power of the spring 35. The screen 33 is of uniform density and may be of the type shown in Figure 22 or of that of Figure 23.

As another signal appears, it may operate a photoelectric cell 41 through the mirror i6. The cell 41 through a lead 43 operates a magnet 49 which moves a switch bar 50 to position to close a circuit through a lead 5! which operates a solenoid 53, which corresponds to the solenoid 32. Means attaching the solenoid 53 and its screen 53 may be the same as previously described for the solenoid 32 and the screen 33. This solenoid 53 will swing a screen 5| into light intercepting position. This screen is of uniform density, but of a density different from that of screen 33. As the screen 54 reaches the detent H its forwardly extending portion correspond ing to the formation 40 will raise the detent 4! against the power of a spring 43 long enough to release the formation 30 for the screen 33 to be removed from light intercepting position by its spring 35.

The mirror i5, when actuated by the appropriate signal on the film, in cooperation with a photo-electric cell 51 and a lead 33, operates a magnet 53 which moves a switch element to position to close a circuit through a lead 6| which operates a solenoid 62 which brings a screen 63 into position, as previously described for the screens 33 and 54. As the screen G3, which is of a density different from that of screens 33 and BI, is brought into position, any other screen which may then be in position will be snapped back out of the beam of light. as previously described. In Figure 1, we illustrate our invention as applied to a mechanism employing three screens only, but any desired number may be used. It is to be understood that more thanoneof thescreensmaybeoperatedtothe light intercepting position at the same time. Any appropriate combination may be employed, merely by using more than one signal simultaneously.

As is best shown in Figure 15, a protective enclosure surrounds the beam of light from the source II, but permits portions 91 from such light to pass along externally thereof, such portions being effective to operate the signalling devices previously. described. Openings 99 in this protective element are provided for the reception of screens 98, N and l3. 7

Various types of apertures suitable for use with our invention are shown in Figures 3, 4,- and 9. If desired mirrors II, It and H may be placed behind suitable openings and immediately below a space 12 corresponding to'the picture area of the film to cooperate with signals placed between the picture areas, as shown in Figure 6, or a similar construction with various mirrors 13 as shown in Figure 5 placed at the top of the space 16 may be employed, all as taught in our parent applications. It will of course be understood that any convenient arrangement of mirrors may be employed, as taught in our original parent 1 application, or photo-electric cells or the like may be placed directly line with a suitable light transmitting aperture.

A convenient arrangement of signalling aperture and its associated parts is shown in Figure 9. A pilot light 1! projects a beam through asignalling aperture I9 in a pilot gate 11 and upon a mirror ll, which directs a signalling beam upon a radiant responsive element, as upon a cell I18 later described.

Instead of placing uniform density screens in the beam of the printing light, as shown in Figure 10 we may accomplish the same result by means of resistance added to the circuit of a printing light. In such cases we pass light from a source 18 through condensing lenses I9 and a negative film 88, and across the path of a shutter ii, if desired, and upon mirrors 92, I9 and 84 which cooperate with various photo-electric cells or the like. Since the printing light itself changes from time to time owing to the addition of resistance to its line and its removal therefrom it is necessary in this form of our invention to supply pilot lights 85 and 98 which are of constant intensity, suitably baiiled from the .re mainder of the apparatus, to operate the signalling circuits. Light from the source 85 passes to the mirror 92 and thenc to the photo-electric cell or the like 81 and through a lead 89 operates a magnet 89 to move a switch arm 99 to close a circuit through a lead 9| which through a switch arm 93 closes a circuit to a resistance 94 in circuit with the printing light source 18. As will be readily apparent from Figure 10, as the switch arm 93 is moved to the right its end, suitably insulated will contact with a cam surface 95 upon a bar 96 and raise this bar against the influence of a spring 91. If at this time any other switch bar is in contact, it will immediately snap out of contact under the influence of its spring, unless the circuit to its controlling solenoid is then also closed.

Similarly through the mirror 83, a signal, re sponsi've to light passed by the pilot light 88, will actuate a photo-electric cell 99 which through gnaw a lead I" operates a magnet Ill which moves a switch bar ill into position to close a circuit through a lead I93 which operates a solenoid Ill to move a switch bar Ill into position to close a circuit through a lead "1 and a resistance ill tothe printing light 18.

Similarly a signal carried by the film cooperates with the mirror at to actuate a photoelectric cell III which through a lead H2 operates a magnet III to move a switch bar HI into contact with a lead 5 which closes a circuit to a solenoid H9 which pulls a switch and Ill into position to cooperate with a lead 9 to close a circuit through a resistance I29 to the light source II. I

As previously described in connection with the form of the invention shown in Figure 1,- several of the foregoing resistance tmits may be operated simultaneously and the number may be increased as desired. It is to be understood that when any incandescent light source is reduced in voltage below a certain point its color characteristics change. Under certain conditions, therefore, in order to avoid such changes it is desirable to place a color filter lit in the light beam so that the printing is carried out by monochromatic light.

spond exactly to the resistance element I29 and be operated in a similar manner. As its resistance is placed in the motor circuit, the speed of the sprocket I29 will be decreased while a printing lamp 18 remains constant. Other resistance elements, exactly corresponding to 94 and Ill of Figure 10, may be added to the structure of Figure 11 and operated in exactly the sameway. Such additional resistance elements, therefore, need not be illustrated and described in detail. If desired through separate signalling operations the screens of Figure 1 and the resistances of Figures 10 and 11 may be combined.

Figure 12 shows a preferred modification oi the device of Figures 10 and 11. As a resistance wiping arm I3l is moved by a solenoid It! to the right as viewed in Figure 11, it moves across a variable resistance I33 which is in circuit with the motor M, thus gradually instead of suddenly decreasing its speed and hence slowly changing the intensity of the printing light. Similarly, as

the arm I31 is released by the raising of the detent I 35, which corresponds to the detents 4|, the arm ill moves relatively slowly to the left under the influence of a dash-pct I31. It will thus be seen that we have provided'means automatically fading in and "fading out" in response to pre-determined signalling operations. The solenoid I32 may be operated exactly as are the solenoids 92, I94 and H8.

As previously stated, if desired, instead of changing the density of the positive fllm to be printed or the positive resulting from the reversal of a negative by means of signals predeterminedly placed thereon we may determine such density by the density of the negative film itself.

As previously stated, instead of depending upon signals predeterminedly placed upon the negative film for the automatic or other actuation of the machanism by which the intensity of the printing light is changed, we may depend upon the density of the negative film itself.

As is shown in Figures 13 and 14, we may operate our invention in part manually. A negative film I40 may pass through a signalling gate I with an aperture through which a signal light I42 passes a beam which impinges upon a photoelectric cell I48, the current from which is amplified in any well known desired way as indicated at I44. Such amplified current passes through a winding I45 which operates a core I45. Attached to this core is a pointer I41 which is moved in one direction by the strength of the attraction exerted upon the core by the winding and moved in the other direction by a spring I48. The end of the pointer cooperates with markings I49 which indicate the density'of the negative.

A printing light II projects a beam upon a printing gate I52 through which, if desired, a positive film I59 may also be passed. The negative film and the positive film, if employed, are both fed by a sprocket I54 which is driven through any desired connection (not shown) by a motor I55. A series of screens I55, each provided with a handle I51 are mounted for movement from and to positions wherein they intercept the beam oi light passin from the source I5I to the printing gate I52. As the operator wishes to make a major change in the intensity of the printing light, he manually moves one or more of these screens as desired. resistance I58 is arranged for inclusion in the circuit of the motor I55 by means of a wiper arm I59 operated by a handle I50. To efiectuate the desired minor changes in the intensity of the printing light, the operator moves the handle I60 thereby decreasing or increasing the resistance in circuit with,the motor and hence the time of exposure and the eflectiveness of the printing light.

Figure 14 shows an alternative arrangement in which a pilot light source I6I illuminates a ground glass or similar material I62 and a sight-' ing aperture I88 through which the operator views the negative film as it passes by, and changes the printing intensity. In accordance with his Judgment, he operates the screens I55 and the resistance I59.

The two forms of our invention shown above are particularly applicable when a negative is to be reversed into a positive and pre-timing is not practicable. It may be used however, for a printing operation and is particularly useful in the quick making of rough first prints or rushes.

Figure 16 shows the form of our invention shown in Figures 1, 9, l0 and 11 applied to the printing of a positive film I55 from a negative film II' as at a printing aperture 14'.

Obviously the light which is passed through any image will vary inversely as the density of that image and hence will form a sufiiciently accurate guide to the printing light which should be projected through that image in order to secure a uniform result.

In the form of our invention shown in Figure 1'1, we pass a negative film I through the pilot gate 11. The pilot light source 15 directs light through the film at an aperture 15 and upon a mirror I4. Thereupon it may be reflected by the mirror I4 upon a cell I18.

A variable may be introduced. It will be readily under-' stood that the printing operation may be of the continuous or step type. The printing operation as such forms no part of the present invention, since the present invention lies in the control of the printing operation and not in the printing operation per se.

Current proceeding from the photo-electric cell I18 is amplified in any desired manner as indicated at I84. The amplified current proceeds,

through a lead I .to a winding I88 which controls a core I81 pivoted at I88 and carrying a wiper arm I89 which cooperates with a variable resistance I90 which is in circuit with the light source I82. It will thus be readily understood that as the current which passes from the amplifying element I84 is increased in response to an increased efi'ective brilliance in the light passing from the pilot light 15 through a negative film I15 0! less density, the wiper arm I89 will be moved to the right as shown in Figure 15 and more resistance placed in the circuit of the light source I82 thus decreasing its efiectiveness and decreasing the printing light. Similarly when the amplified current is diminished, a spring I9I will pull the wiper arm I89 to the left as viewed in the drawings thus increasing the brilliance and efi'ectiveness of the light source I82.

If a radiant-responsive element I19 is used which increases its electrical output as the light impinging upon it is decreased, the resistance I90 is arranged so that the movement of the wiper arm I89 to the right decreases instead of increases the resistance in circuit with the printing light source I82. In either case, it will be understood that the effective light output 01. the two light sources always varies inversely.

Figure 18 shows similar apparatus but applied to the control of the printing operation by means of changes in the speed of the drive of the film as it passes through a printing light. As pre viously explained, it will be understood that the amount of the exposure and consequently the density 01' the reversed or positive film is directly varied as is the time of exposure at the aperture. Consequently, if the speed of movement of the film be decreased, the exposure will be greater and the resulting positive subjected to a greater efiective printing or reversal light while on the other hand it the speed of movement oi the film is increased the exposure will be shorter and tlhe positive subjected to a printing or reversal l ght.

As shown in Figure 18, a negative film I99 may be drawn through a pilot gate I94 through which a pilot light I95 passes light which controls a photo-electric cell I98. Thereupon the negative film, and a positive film I91 if desired, may be drawn through a printing gate I 98 under the influence of a printing light I99 by a sprocket 200 driven in any desired or conventional way by a motor MI. The current proceeding from the cell I96, which corresponds to the cell I18, is amplified as indicated at 203. Through a lead 204 the amplified current is passed through a winding which attracts a core 2% which.

. pivoted at 281 for movement with a resistance wiper arm 2% against the power of The wiper arm 203 passes over a variable re slstence Ell which is connected in series with the motor 2M. Consequently the amount of resistance in this circuit and hence the speed of operation of the film and the resulting density of printing are conditioned by the amount of light passed through the negative film by the pilot light I95. If the efiectlve electrical output of the cell I98 is increased in direct proportion to the light impinging upon it, the resistance 21! is so connected in the circuit of the motor 201 that this increase in efiective brilliance of the pilot light decreases the amount of resistancein circult with the motor and hence increases its speed but with a resulting decrease in printing efiec tiveness of the printing light I99, as shown in Figure 18.

light 2| 1 which controls an element 218 respon-- slve to radiant energy and then through a printing gate 220 drawn by a sprocket 2 past a printing light 222, the positive film 223 being introduced at this point, if desired, and passed with the negative film past the printing light 222. The current, proceeding from the element 2| 8 is amplified as at 226. The amplified current through a lead 221 is passed through a winding 223 which controls a core 228 pivoted at 230 and carrying a wiper arm 23I= which through a resistance 232 controls the amount of current passing iroma battery through a special braking winding 233 in the shunt wound motor 234 which drives the sprocket 221 in any conventional or desired manner, As previously explained the amount of amplified current passing through the winding 223 determines the position of the core 229 and consequently the amount of current passing through the resistance 232 which in turn determines the amount of currentpassing through the winding 233. As will be readily understood by those skilled in the electrical art the current passing through the winding 233 may be arranged to set up a counter electromotive force which is in effect a braking action which directly and accurately determines the effective speed of the motor 234. It will thus be understood that the amount of light to which the films 215 and 223 is subjected from the printing light source 222, is accurately controlled by the light; which impinges upon the pilot photo-electric cell 218.

Figure 18 shows anothermodlfication of our invention in which the speed of the motor is controlled by braking mechanism of the pump type, long recognized as extremely accurate.

A negative film 24K is moved through a pilot gate 242 and a printing gate 243 by a sprocket 244 which is driven in a manner later described by a motor 245. In the pilot gate the negative is subjected to light from a pilot light 241 which passes through the film and upon a photo-electric cell 248. The printing light 249 is maintained at a constant level of intensity. The current proceeding from the cell 248 is amplified as at 251 and through a lead 252 passes through a assess? winding which controls a core 254 pivoted for movement with a pinion 255 and movable against the influence of a spring 255 attached to an are which moves with the core 254. The pinion 255 through a. gear 25? operates a toothed bar 258 one end of which is formed into a needle point 259. It will be seen, therei'ore, that the needle point is moved in accordance with the amount of current passing through the winding 253. Gears 260 form a portion of a train which transmits motion from the motor 245 to the sprocket 244. These gears work in a housing 26I which has a connection 282 with the oil reservoir 263. The revolution of the gears 252 will pump oil from the reservoir 233 past the needle 258 and through a tube 234. The amount of the opening in the tube 234, whlch is determined by the position of the needle 2", will, of course, determine the speed of the flow of the 011. As is well understood the resistance which the fiow of the oil applies to the gears 26. forms one of the most accurate and dependable braking mechanisms which is in use. A relief valve 265 is provided to take care of emergencies.

As previously stated in this specification, under I many circumstances we prefer to secure the relatively large gradations of light by means of the interposition of a series of screens of uniform density and the minor variations by changes in the speed of film movement or intensity of the light at its source. The accuracy, elasticity and efilciency of such operations are apparent.

Figure 21 shows diagrammatically. a preferred form of our invention, in which the operation is entirely automatic, and the gradations are seis then drawn through a printing gate 219 by a sprocket 280 and subjected to a printing light from a source 281. At this point, if our invention is applied to a printing process, a'posltlve film 283 may be introduced. The current proceeding from. the element 218 is amplified in any desired or conventional apparatus generally indicated at 286. The amplified current thence proceeds through a lead 281 t0.a first of a succession of closely interrelated controlling units. It will be assumed that the operation of the apparatus is started at the point in which the desired intensity of the printing light is as great as possible so that thereafter a maximum amount; of obscuration is introduced into the light beam.

'0 this point, the negative being of maximum density, a minimum amount of light is passing therethrough and impinging upon the cell 213. The amplified current from the lead 281 passes to a winding 283 which controls the movement of the core pivoted at 289 and carrying a wiper and switching arm 290 which operates a resistance 291 in circuit with the light source 281. As previously explained, an increase in the effectiveness of the amplified current will move the wiper arm 250 to the right as viewed in Figure 21 against the power of a spring 292,'thus placlng more of the resistance 29! in circuit with the light source 28I, while a lessening of this current will permit the spring 292 to move the arm 280 to the left and. thus increase the amount of current passing through the light source. If the current passing through the lead m is sufficient to move the arm 233 the entire distance to the right, a switch block 294 supported thereupon and insulated therefrom contacts with the switch points 233 thus closing a circuit to a solenoid 233 which thereupon moves a switch arm 291 downwardly as viewed in Figure 21, thus breaking the previous circuit through the winding 233 and making a circuit through a lead 233 which operates a solenoid 233 to pull a switch arm 300 upwardly, as viewed in Figure 21, thus closing a circuit through a winding 302 and permitting the amplified current to pass therethrough. The operation of the solenoid 293 is also effective, as clearly shown in Figure 26, to move a screen 303 into light intercepting position and thus place the apparatus fully in the second stage of obscuration. Solenoids 233 and 304 are Joined by a shaft 303 to which an arm 331 operating a link 303 is applied. Alink 303 pivoted at 3" through a'pin and slot connection 3| 1 operates the screen 303. The actuation of the solenoid 293 moves the screen 303 from full line or non-shielding position to the dotted line or shielding position of Figure 26, while the actuation of the solenoid 304 will be effective to move the screen 303 from the dotted line to the full line position. The utility of the pin and slot connection will later be apparent in connection with later stages hereinbelow described. It is not necessary for the first and last stages, but as a matter of manufacturing practice we may prefer to make all connecting mechanism alike. It will be readily understood that when th circuit through the winding 233 and the switch arm 291 is broken, the spring 232 will snap the .arm 290 back to the neutral position.

It will be noted that as the switch arm 300 moves upwardly to close a circuit including the winding 302, it first impinges upon an elongated contact 3l3 which closes a circuit through the winding 302'before a lead 3 is energized, thus moving the core 3l3, which is pivoted at 3l3, and the contact and switch arm 3" mounted for movement therewith to the right before a switch member 3l3 mounted upon the switch arm 3H and insulated therefrom can become effective to energize two circuits, including one leading to the solenoid 304, which are controlled thereby. Increase of the amplified current through the winding 302 will be effective, as previously described, to move the arm 3H forwardly over a resistance 3l9, thus decreasing the effectiveness of the printing light source 28!. When this signalling current becomes sufiiciently great to move the arm 3i1 completely to the right as viewed in Figure 21, switch points 32l will be effective to close a circuit which through appropriate leads operates both parts 323 and 324 of a solenoid which is opposed to the solenoid 299. Such operation will be efi'ective to move the switch arm 300 downwardly so that it breaks the circuit through the winding302 and makes a circuit through a lead 321. To move the switch bar 300 clear of the elongated contact 3l3 after the circuit through the winding 323 is broken, a simple toggle is applied which is an exact duplicate. except in the length and power of its spring 321' of the toggle later described in connection with the switch bar 330. The power and length of the spring 321' are merely sufficient to move the switch bar 330 to the neutral position as shown in full line. This operation of the solenoid windings 323-324 also moves a screen 326 into light intercepting position, through mechanism, prebase viously described, such as is shown in Figure 26. The lead 321 directly corresponds to the lead 293 previously described, and operates another stage of obscuration through unit mechanism which is an exact counterpart of that which has just been described. Any number of such stages, each a complete unit as described above, may be interposed between the second and final units above and later described respectively. In order to savespace, since each of these units is identical with the others, description and illustration of them is omitted.

The lead corresponding to 321 in next to the final stage of obscuration is attached to a lead 323 which operates a solenoid 323 to draw a switch arm 330 upwardly to complete a circuit from the lead 231 through a winding 332 and at the same time breaks a circuit through the previous winding of the unit last previously in the line of succession, that is to say, the winding corresponding to 302 described above. As in the previously described unit, an elongated contact point 332' is supplied. The winding 332 operates a core 333 pivoted at 334 and operating a switch and contact arm 333 as previously described.

After the contact arm 334 is moved by a sprin 333 to the left, owing to a decrease in the intensity of the signalling light, the reverse movement through the several units representing the several stages of obscuration takes place. A switch block 331 mounted upon the arm 335 and insulated therefrom through a lead 338 operates a solenoid 339 to break a circuit through the winding 332, and operates a lead 340 which is connected to a lead corresponding to a lead 341 in the control unit adjacent that which operates the final stage. In order to move the switch arm 330 completely off of the elongated switch point 332' controlling the winding 332 a simple toggle is supplied. This toggle comprises a rod 342 pivotally attached to the arm 330 and working in a guiding opening in a member 343 pivoted upon a A relatively weak spring 344 working between the member 343 and a collar 345 quickly moves the switch 330 to the full line position after the first short movement of the solenoid 333. Thereupon, the circuit to this solenoid is broken. The corresponding lead in the control unit adjacent the one shown in the drawings as intermediate the first and last units in the line on erates the solenoid 299 which removes the screen 326 from operative position and closes the 300-3i3 and sets the toggle, thus again p the arm 3i1. in operation for as long a. par may be signalled. When the signalling current passing through the lead 281 and switch arm 30!? becomes diminished to a predetermined point, it moves the arm 311 completely to the left, thus through the switch block 313 mounted upon and insulated from the arm 3|1 closing a lead 341 which operates only one of the windings 323 of the double-wound solenoid previously described, thus, with the aid of the previously described toggle, pulling the switch bar 300 to a neutral position. Owing to the pin and slot connection previously described. this movement has no effect upon the screen 323, which has previously been removed from light obscuring position. The switch block 313. through a lead 349, likewise opcrates the solenoid 304 which moves the switch bar 291 into such position that the control cur rent again passes through the winding 233. This operation of the solenoid 304 also removes the screen 303 from efiective relation to the film. In the above description of our invention it has (LI:,L

been assumed that the progression of the changes intensity will be re Jar from one stage to an other, and then hack. and .Ji. It is of course under stood that as a matter oi. fact 'hese changes will be irregular will go from one stage to another in either direction or may fluctuate within one stage for a long period.

As shown in Figure 22, the several light obscur lng elements 363 and. 32d and those intervening are formed of a material of uniform density which changes the amount of light which passes therethrough without changing its rate of vibration. Such filters are commonly made of ground glass or are gray in tone. In Figure 23, as a preferred modification, we show filters 303' and 326' and those intervening which are composed of metallic mesh of varying degrees of fineness. The advantages of such light retarding means include a large reduction in the heat which passes from the light source to the film without any change in printing effectiveness. This reduction is particularly important in such case as those in which our invention is applied to the reversal of a negative to a positive. In this process the negative is handled wet, or' at least moist, and the ill efl'ects of undue heat from the printing light source are more marked than with a dry film.

Alternatively to such movable screens, diaphragms may be employed and controlled simi- 1arly,'

Figure 25 shows a printing light source 28l' with a metallic mesh screen 3 permanently in the light beam in order to reduce the heat at all stages. Any other heat reducing medium may be employed. In addition, the screens described above, it desired, may be employed. The advantage of this plan is that it permits a light source of higher intensity to be used, and then filters out a certain amount of the heat without changing the light characteristics. Such a light source burned below its full intensity is not so likely to fluctuate with minor voltage variations, lasts much longer, and well lends itself to control by means of changes in the resistance in its circuit, as described above, since changes in intensity can be efiectuated without changing color values, as is not possible with an incandescent light source burned to a critical intensity.

Instead of. efiectuating the minor variations as above by means the introduction of resistance into the circuit of the light source, such minor variations may beaccomplished by introducing resistance'in the motor circuit, asshown in Figure l8 hereof, or using the mot-or brakes of Figures 19 and 20, in each case with the stages of obscuration and screens as above described.

In any form of our invention in case the pilot or signalling aperture is placed for convenience a considerable distance from the printing aperture, any suitable time-conserving electrical element or relay may he placed at any convenient point in the circuits controlled by the current passing from the signalling cell so that the changes in intensity at the printing aperture are properly timed.

If the photoelectric material is so transparent as to cause neither shadow nor distortion, it may be introduced directly into the pathway of the image-bearing light (that is, between negative and positive) and the use of more than one aperture or of a reflecting means rendered unnecessary.

Still another arrangement is to place the photoelectric material on the side of the positive film opposite to that from which the light is projected.

this plan the relatively small amount of light which passes through the positive film serves the control element. Consequently the photoelectric material must be of much greater sensitivcness, out the complication of defiectedlight or oi two apertures and a time element are elirnihated. The undeveloped positive films are of sutdoiently uniform density to render the variations in light which is projected through them of no practical consequence.

Different portions of each individual picture or frame in certain negatives may diiler so widely as to make it desirable to make certain that the average density of the entire frame rather than the density of widely difl'ering portions or it control the intensity of the light. This result can be achieved by the introduction into the path of the image-bearing light of a properly designed lens.

Instead of varying the intensity of the light by changing the intensity of the light-source, it is sometimes desirable to vary the amount of light which is allowed to become effective. This result is accomplished by placing a diaphragm or iris in train with light-source, negative, photoelectric material and positive, and, by means of suitable electrical and mechanical means, causing the diaphragm to increase or diminish its diameter in accordance with the amount of current which flows through the photoelectric material.

When the positive film is to be tinted,'toned, or colored, or for other reasons, it may be desired to print a certain picture more or less heavily than is normal. To meet this need, our invention provides that the resistance control member may be set at will a few points above or below normal, so that the automatic operation will be correspondingly (and uniformly) changed until this member is reset.

It will be readily understood that the application oi this invention includes photographic printing of all kinds. The negatives may be in the form of films, single or in strips or rolls, or of, glass plates, or the images from which the printing is done may be opaque, and the printing process by means of reflected light. Similarly, the positive prints may be single, or in strips, sheets or rolls, and of any material, including inter alia, Celluloid, paper, fabrics and glass.

As previously pointed out, our invention in all of its several aspects may be applied equally well either to a printing process in which a positive is reproduced from a negative or to a reversal process in which a negative is changed into a positive. Figure 24 shows the invention applied to a reversal process. A negative film 349 in process of reversal is fed through a pilot gate 2% and under the influence of a non-actinic pilot light 211' which operates a'cell or a thermocouple 258, and through a printing gate 219' in which a printing light 28E" through an aperture 35d reexposes the negative so that a positive ultimately results. The control of the printing light 233 by the cell 218' is exactly as described above for the light 28i by the cell 218.

Many of the characteristics, objects and advantages of our invention will be evident from the drawings which are a part hereof and from the foregoing portion of this specification. These advantages include the provision of a simple method whereby intensity of a printing or reversal light may be controlled either manually.

or automatically, preferably through several Qfilidfi 7 thereby securing major gradations in the photostages, one instrumentality establishing the major gradation of each stage and another instrumentality determining the finer gradations within each stage. Other advantages flow from the provisionof anautomatic printing controi whereby electrical resistance is used to vary the printing or reversal light or the speed of the motor. Still other advantages fiow from the provision of method and apparatus whereby a photoelectric control automatically operates the intensity of printing or reversal lights.

We claim:

1. In a single substantially continuous motion picture printing operation, the method of changing the eiiectiveness of aprinting light which comprises both modiiying the light which is emitted by the source and changing the capacity of the source to emit light, one of such modifications being employed to secure the minor variations while the other of such changes is being employed to secure the major variations during such printing operation.

2. The method of substantially continuously producing a single motion picture film bearing successive positive images of uniform density from successive negative images cinch-uniform density which comprises moving a film bearing negative images past a light source, interposing a succession of light obscuring means between th light source and the film for accomplishing the major variations, and between the interposition of each of said light obscuring means changing the amount of resistance in circuit with said light source for securing the finer variations which are desired.

3. In a motion picture printing operation, the method of changing the eilectiveness of the light which is employed to produce a series of positive images of uniform density from a series of negative images oi! non-uniform density which comprises moving a film which is to bear said positive images past a light source, modifying the capacity of said source to deliver light to said negative images and to said film, reducing the amount of light passed between said source and the film, and determining the amount of such reduction and modification in accordance with the density of the negative images irom which said positive images are being reproduced.

4. The method of carrying out a motion picture photographic printing operation which comprises moving a film past a light source, relatively inirequently interposing light diminishing means between the light source and the film to obtain a relatively large change of fixed amount in the effectiveness of the light source on the film, and between the times at which said light diminishing means are interposed making relatively slight and frequent variations in the resistance in circuit with said light source to ob-- tain finer gradations in the effectiveness of the printing light.

5. The method of producing a motion picture film bearing positive images or uniform density from negative images of non-uniform density which comprises moving a film bearing negative images past a light source, determining the d11- ierences in the density of said negative images by passing radiant energy through said negative images and upon a substance responsive to the changes made in said energy by the diiierences therein caused by the difierences in density 0! the negative images, materially changing the amount of light from said source which reaches the film-in accordance with such determination graphic efiectiveness of such printing light, and likewise in accordance with such determination slightly varying the amount of resistance in circuit with said light source thereby securing minor gradations in such photographic effectiveness.

6- The method of substantially continuously producing a single motion picture film bearing positive images of uniiorm density from successive negative images of varying density which comprises moving a film bearing n t v i es past a light source, successively placing a series oi light retarding instrumentalities o! markedly difierent densities in the path of light, and gradually varying the photographic effectiveness of the printing light between the time of the interposition of one of said instrumentalities in said path and that at which another is so interposed.

'7. The method of substantially continuously producing a single motion picture film hearing positive images oi uniform density from successive negative images of varying density which comprises moving a film bearing negative images pasta light'source, successively and selectively placing a series of light retarding instrumentalities of difierlng powers in the path of light to secure major gradations in printing density, gradually and relatively slightly varying the effectiveness of the printing light in order to secure minor gradations, and using the variations in density of the negative images to determine which oi said light retarding instrumentalities shall be employed and also to determine the slight variations in the efiectiveness oi! the printing light.

8. In a motion picture photographic printing apparatus, a printing light source, means for directing light from said source upon a film, a plurality of light diminishing screens, each movable to and from .operative light reducing position, means operable for separately moving each of said screens to its operative position, and means actuated by portions of the film of predeter- -minedly changed translucency Ior operating said screen moving means, the film being formed with such portions.

9. In a motion picture photographic printing apparatus, a printing light source, means for directing light from said source upon a film, a plurality oi light diminishing screens, each movable to and from operative light reducing position, means operable for separately moving each of said screens to its operative position, means actuated by portions of the film of predeterminedly changed translucency for operating said screen moving means, and means operated concomitantly with the operation of said screen moving means for removing the screen last previously disposed in operative position i'romsuch position, the film being formed with such portions 01' predeterminedly changed translucency.

10. In a motion picture film printer, a source of printing light, means for feeding a film hearing successive images of varying degrees of density through light from said source, a plurality of light modifying screens, a separate movable mount for each of said screens, separate and successively operable operating means for moving each of said mounts and the screen carried thereby in relation to the path of light from said source, actuating means controlled by the differences in density of said successive images for actuating each of said operating means, andmeans controlled concomitantly with the operation of each of said operating means (or rendering another of said operating means operable by said actuating means whereby said actuating means under the control of the diflerences in density of successive portions of the film selectively operates said screens.

11. In a motion picture film printer, a source of printing light, a plurality of instrumentalities each movable into and out of effective relation to said printing light, magnetic means for moving each 01 said lnstrumentalities in relation to said printing light, each of said magnetic means including a control circuit, means operated by the movement-of each of said magnetic means to close the control circuit of another or said magnetic means and to open its own control circuit. and means for operating each of said magnetic means through its control circuit.

12. In a motion picture film printer, a source oper ting l its cont oi nit.

13. In motion picture photographic printing paratus, ll'l combination, an electric printing p, at least one control lamp positioned for pcslug ligrt through predetermined portions of the him having a translucency difi'erent .Erour other corresponding portions, the film being pro= vided with such portions, a, plurality of electric resistance elements, means operable for separate ly connecting each of said resistance elements in the circuit or said printing lamp, electric means i'or separately operating each of said resistance connecting means, and means for actuating said electric means by said portions of the film having a dlfierent translucency.

14. In a motion picture photographic printing apparatus, in combination, an electric printing lamp, at least one control lamp positioned adjacent each side 01 the film for passing light through predetermined side edge portions of the film having a translucency different from other corresponding portions, the film being provided with such portions, a plurality of electric resistance elements, means for connecting each of said resistance elements with a source of power, means operable for separately operating each of said resistance connecting means, and means Ior actuating said operating means by said portions of the film having changed translucency, said last named means including a separate photoelectric cell arranged for cooperation with each of said control lamps.

15. In a motion picture film printer, a source 01' light, means for moving a film bearing successive negative images through light from said source, a first means for reducing said light at such source, a second means for reducing the amount of light transmitted from said source to the film, and control means operatively interconnecting said first and second light reducing means and including devices for necessarily operating one thereof simultaneously with and as supplemental to the operation of the other thereof.

16. In a motion picture film printer, a source of light, means for moving a film bearing successive negative images through'light from said source, a first means for changing the amount of light emitted by said source, a second means for changing the amount of light which can pass from said source and impinge upon the film, control means responsive to changes in the density of said successive images, and means operatively interconnecting said density responsive means and said first and second light changing means and including devices for necessarily operating said first and second means simultaneously and in accordance with variations in density oi said successive images.

17. In a 'motion picture film printer, a source of light, means for feeding a film bearing successive negative images through light from. said source, a first means for modifying said light at its source, a second means for modifying said light between its source and the film, and means actuated by one of said light modifying means for operating the other of said light modifying means.

in a motion picture film printer, 9. light source, means for feeding: bea g success-- sive negative images through light I. source, means for modifying the emitted by said source, means for light between said source and ti modifying means having a predetermined ro ge operation, control means onsive to changes in the density of succe lve images, operative interconnection between. said density responsive means and one of modifying I m ans for operating said means in. accordance 1 said changes in density, and an operative w; interconnection between the other of said anodiiying means said density responsive means for operating said modifying means at an extreme point in the range of operation of said first mentioned modifying means.

19. In a motion picture printing apparatus, a light source, means for feeding a film having successive negative images of clifierent degrees of density through light from said source, control means responsive to the density of said successive images, a plurality of unit mechanisms each having instrumentalities for modifying the effectiveness of light from said source impinging upon the film, each of said light modifying means being eifective within a predetermined range and representing successive stages of photographic light values, a connection between said unit mechanisms for rendering one of said unit mechanisms inoperative at an extreme point in its range of operation and for rendering the next unit mechanism in stage of light value operable, and means operated by said density responsive control means for operating each of said unit mechanisms within its own range of values.

' 20. In a motion picture printing apparatus, a printing light, a plurality of unit mechanisms each having means for changing the amount of resistance in circuit with said light source, operative interconnection between said unit mechanisms for rendering one of said mechanisms inoperable and another of said mechanisms operable when a predetermined amount of resistance has been introduced into said circuit by the first mentioned of said unit mechanisms, and means responsive to the density of said negative images for operating said resistance means of each of said unit mechanisms.

2'1. In a motion picture film printer, a source of printing light, means for changing the effectivenessof light from said source reaching a movement of said screen is carried out concomifllm having successive portions of varying detantly with such gradual changes in the effecgrees of density, said means including a plurality tiveness of said light source.

of rheostats, each of said rheostats having a cir- 26. In a motion picture film printer, a source cult and a wiper arm which carries a switch eleof light, means for moving a film bearing sucment which when said wiper arm is moved to a cessive images of varying degrees of density predetermined position will break the circuit of through light from said source, a series of light said rheostat and close the circuit to another of modifying instrumentalities each movable into said rheostats, and means for moving said wiper the path of light from said source, each of said arm to said predetermined position, 10 instrumentalities having a markedly different 22. In a motion picture film printer, a source i ht mo i yin ffe and h r pr en n a of printing light, means for changing the eflecdistinct stage of light intensity, means for movtiveness of light fr m aid urc r achin a ing each of said instrumentalities into the path film having successive portions of va in d of light from said source, means associated with grees of density, aid m a i l di a l ralit 10 each of said instrumentalities for gradually of rheostats, each of said rheostats having a circhang the effectiveness of Said light w e cult and a wiper arm which carrie m i each of said instrumentalities is in effective relament which when said wiper arm is moved to a thin to the light thereby Slightly modifying t e predetermined position will break the circuit of effectiveness Said Printing light, each of said said rheostat and close the circuit to another of means r r u y changing e l gh h vin said rheostats, and means controlled by the vara predetermined range of movement, on ro iations in density of the film for moving said mechanism p a d y s d m in means in a wiper arm to said predetermined p051tn first of said stages for placing the moving means 23. In a motion picture film printer, a source p y t a ec o S d sta es in such conof light, means for m vin a film bearing dition that it can be operated, and means opercessive images of varying degrees of density flied y the means for gradually changing he efthrough light from said source, an inst fectiveness of the printing light associated with tality movable into and out of the path of light said. moving means of d fi st sta e for renderfrom said source for markedly modifying the ef- 8 the moving means of Said Second S e p fectiveness of said light, means for moving said able when Said means for gradually Changing instrumentality, auxiliary means separate from said light reaches a predetermined position in its said modifying means for slightly modifying said range ov eifectiveness, and control means for said auxil- In a motion Picture film p a ource iary means operated by the movement of said 0! light. means for moving 11 mm be S omoving means. cessive images of varying degrees of density 24. In a motion pictur 111m ri t source through light from said source, a series of sepaof light, means for movin a f l bearing rate means for changing the effectiveness of said cessive images of varying degrees of density l t. pa operating means for successively through light from said source, an instrumen- 40 renderih! Belch of said light c ng means eftality movable into and out of the path of light fective, s p te withdrawing means for succesfrom said source for markedly modifying the efsively and separately e de i ea of s id ht fectiveness of said light, means for moving said changing meens'inefi'ective. nd control mechainstrumentality, auxiliary mea separate from nism necessarily effective to render operative the Said modifying a s for slightly modifying said one of said withdrawing means which is associeffectiveness, a circuit for operating said auxilated with iihe light 8 8 a s which is then iary meansQmeans controlled by variations in operative and u t y to nde operative the density of said successive images for feeding another Said light c a e s.

said circuit thereby operating said auxiliary In a motion pi e fi m Prin 8 Source means, and a switch for said'circuit operated by of light, m s f r m vin a lm ar n su the movement of aid moving means, cessive negative images through light from said 25. In a motion picture film printer, 9. source Source, a Series Of light modifying s ru enta of printing light, means for feeding a film bearties each movable into the P 0 fi o ing succe siv negative ima of v i said source, separate means for successively movsity through light from said source, gradually op- 8 each 0! S ihstrilmehtalities 111190 the P erable resistance in series with said light source, of light from aid o r e. s parate means for resaid resistance including a movable wiper arm. moving each 01 Said instrumehtamies. from B d an armature operatively connected with said path of light, and mechanism necessarily operwiper arm for operating said arm, a coil for movative to actuate the one of said removing means ing said armature, a photo-electric cell, a pilot which is associated with the light modifying inlight for passing light through said images strumentality which is disposed in said path conand upon said cell, means for amplifying the eleccomitantly with the actuating of one of said trical output of said cell, a connection for delivermeans for moving another of said instrumentaliing current from said amplifying means to said ,ties into said path whereby only one of said incoil thereby moving said wiper arm and gradually strumentalities is disposed in said path at any varying the effectiveness of said light source in one time.

accordance with the density of said successive WARREN DUNHAM FOS'I'ER.

images, a light modifying screen, means for mov- PEOPLES-PITTSBURGH TRUST ingx-said screen in relation to light from said COMPANY, printing source before it reaches said images, a 7 Executor of the Last Will and Testament of solenoid for moving said screen, and switching Earle L. Parmelee, Deceased.

means operated by the movement of said wiper By GWILYM A. PRICE, arm for actuating said solenoid whereby the Trust Ofllcer. 

